How important is RAM speed?

November 24, 2010 at 03:29:20
Specs: Windows 7, AthalonX4/4GB
Hi, in my coursework i've been asked to elaborate on a part of it and explain why faster RAM is important. I can't think of the way to word it, and asking google has brought me nothing.

Could anyone help me out?


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November 24, 2010 at 04:08:56
It's not 100% true. It depends the type of cpu u have. For eg. If u have c2d e8400 and ddr 1600 u will loose perforfance, but if u have c2d e8400 and ddr 667 u will gain perfomance.

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November 24, 2010 at 04:44:59
The speed rating of memory is normally given as a single number. That is the number that you use to match the memory to the processor. That is only part of the equation. The latency of the RAM is also important. Read the link below concerning Measurements for more on that.

Buying faster rated RAM and under clocking it can usually result in a lower latency settings. That equates to more data transfer. Or buying the correct speed RAM but with lower latency numbers will accomplish the same thing.

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November 24, 2010 at 07:14:12
"explain why faster RAM is important"

Faster than what? The answer is a lot more complex than you may think. Diiferent CPUs have different memory requirements. Most CPU/RAM configurations have a ratio that should be maintained to provide optimal performance. This ratio is based on the CPU frequency. All CPUs prior to the P4 performed best with a ratio of 1:1, that means with the CPU frequency at 100MHz, the RAM frequency should also be 100MHz. This ensured that both the CPU & RAM bandwidths were in balance.

The ratio requirement changed for the P4 due to the inefficiency of the netburst architecture. The optimal ratios for the P4 are 3:4 for 100MHz or 200MHz frequency or 4:5 for 133MHz frequency. Dual channel mode was also introduced with the P4 to allow the memory bandwidth to keep up with the increased bandwidth of the quad-pumped of FSB.

The Athlon 64 architecture changed the need for a ratio altogether because the FSB was eliminated. With all AMD A64 systems (& newer), the memory should be run in dual channel mode & as fast as possible.

The Core 2 Duo/Core 2 Quad performs best with a ratio of either 1:1 or 1:2, depending on the capabilities of the system.

The latest CPU released from Intel is the Core-i series. This series has also eliminated the FSB so like AMD systems, the memory should be run as fast as possible. The Core-i also introduced triple channel memory.

As OtheHill stated, in some cases it's better to have fast RAM & then underclock it so that the latency setting can be lowered. Let's say you have an old Athlon XP that runs at 133MHz frequency (266MHz FSB) & you install DDR400 RAM which runs at 200MHz frequency & has a latency of 3.0. You know that the optimal ratio is 1:1, so you should lower the RAM frequency to 133MHz (DDR266) to match the CPU. By doing so, you *should* be able to lower the latency to 2.0.

Does any of that make sense?

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